Abstract :
[en] Loosely packed granular materials are intensively studied nowadays. Electrical and thermal transport properties should reflect the granular structure, as well as intrinsic properties. We have compacted crystalline CaAl-based metallic grains and studied the electrical resistivity and the thermoelectric power as a function of temperature (T) from 15 to 300 K. Both properties show three regimes as a function of temperature. It should be pointed out: (i) The electrical resistivity continuously decreases between 15 and 235 K, (ii) with various dependencies, e.g., similar ~ T(-3/4) at low T, while (iii) the thermoelectric power (TEP) is positive, (iv) shows a bump near 60 K, and (v) presents a rather unusual square root of temperature dependence at low temperature. It is argued that these three regimes indicate a competition between geometric and thermal processes-for which a theory seems to be missing in the case of TEP. The microchemical analysis results are also reported, indicating a complex microstructure inherent to the phase diagram peritectic intricacies of this binary alloy. (C) 2004 American Institute of Physics.
Research Center/Unit :
SUPRATECS - Services Universitaires pour la Recherche et les Applications Technologiques de Matériaux Électro-Céramiques, Composites, Supraconducteurs - ULiège
Commentary :
Copyright (2004) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
The following article appeared in J. Appl. Phys. 96, 7338 (2004) and may be found at http://link.aip.org/link/?JAPIAU/96/7338/1.
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